92 THE SALTON SEA. 



It is probable that the species which first obtains possession of an unoccupied mud bank 

 so fills it with its rhizomes as to keep out the other. 



The character of Typha is too well understood to require any comment, but Sdrpus 

 paliidmtis is a little-known species and until now its presence was not even suspected beyond 

 the marshes of Wyoming (where it was first discovered) and of adjacent Utah. It must 

 have descended the Colorado from its distant tributaries, and its colonies will doubtless 

 be discovered along the line of its descent when the flora of these rivers becomes better 

 known. It is plentiful along the Colorado River in the neighborhood of Fort Yuma and, 

 like its companion Typha, has entered the Sink from the delta of that river. 



Scirpus pahidosus is a vigorous perennial sedge, 1 to 23^ feet high, and produces an 

 abundance of seed. Each plant throws out one or more rhizomes about 3 mm. in diam- 

 eter, at the ends of which ovoid tubers are formed which develop new plants. When young 

 these tubers are often an inch in diameter, free from fiber, and edible. As the new plant 

 matures the starch is absorbed and there remains a woody enlargement with a cluster of 

 fibrous roots. The young plants soon become independent by the death of the connect- 

 ing rootstocks and in turn begin to throw out innovating rhizomes of their own. 



It will be readily understood how well such a plant is suited to fluviatile transporta- 

 tion. Not only are the abundant seeds discharged upon the water, but as shifting currents 

 disintegrate a bordering marsh they set free a quantity of young plants, each provided 

 with a store of food-stuffs at its base and ready at once to strike vigorous root as the falling 

 floods deposit it upon some newly formed mud-flat. The same tubers would also serve 

 to carry plants over the seasons of drought to which aquatic vegetation is subject in this 

 region of uncertain water supply. 



In the irrigation canals of Imperial Valley Sdrpus pahidosus is universally present 

 and a source of great annoyance. Its rhizomes fill the mud banks (from which it is prac- 

 tically impossible to remove them), and spread out into the water, checking its current. 



Typha also is frequent along these artificial streams. Indeed, throughout the Sink, 

 wherever an artificial pool or reservoir is made, Typha promptly appears and takes pos- 

 session. 



Cyperus erythrorhizos, an annual sedge, attaining in its best development a height 

 of over 2 feet, and bearing an umbel more than a foot in diameter, but often much reduced 

 in height and inflorescence, is a semi-halophyte, or amphyphyte. It is frequent along the 

 two rivers, but by reason of its reproduction (being entirely by seed), and of its annual 

 duration, its growth is not gregarious. It occupies the banks at the rear of the Scirpus- 

 Typha association, in soil not quite wet enough for them, but when opportunity ofTers it 

 flourishes in water 2 or 3 inches deep. This is not permitted by the vigorous preemptors 

 of the river borders, but it may be seen occasionally along the canals. 



HALOPHYTIC FORMATION. 



Some halophytic associations, limited in extent, have already been indicated as bor- 

 dering the springs described on previous pages. Here are also to be included the salt-grass 

 meadows at the southwestern end of Salton Sea, consisting of a sod of Dislichlis spicata, 

 which holds entire possession of the ground by virtue of its stout, matted rhizomes. 



MECCA-INDIO CHENOPODACEOUS ASSOCIATIONS. 



Far more important are the associations occupying the extensive alkaline flats, stretching 

 from Indio to the borders of Salton Sea near Mecca, a distance of fully 15 miles. Owing to 

 causes already explained, the soil is strongly charged with soluble salts, consisting of sodium 

 chloride, sodium carbonate, and sodium sulphate in dififering proportions, the total saline con- 

 tent varying from 0.5 to over 3 per cent. Over much of the area the water-table is sufficiently 

 high to permit the capillarity of the soil to raise the water to, or nearly to, the surface. 



